Backing-off lathe



Oct 30, 1923. mums- J. DICKESCHEID BACKING-OFF LATHE Filed Aug. 29. 1921 It v 4- Fig.1.

I Jnventor:

' FIN-army.

milling cutter the width of the grooves will increase with.

Patented Oct. 30, 1923.

warren STATES PATENT F ICE.

JOSEF DICKESCHEID, or iuarnz, GERMANY, ,ASSIGNOR TO THE emur: DR. H. znrrn Lem: & 00., err/rams, GERMANY.

BACKING-OFF LATHE.

Application filed August 29,1921.

To all whom z'tmay concern: Be it known that I, JOSEF DIOKESQHIEID, a citizen of the German Republic, and a residentof Mainz, Germany, certain new and useful Improvementsin Backing-OH Lathes, of which the follow- 'ing is a specification. 4

This invention relates to backing-"off lathes, more especially to lathes for backing-ofl milling cutters, screw taps and other revolving tools. In lathes of this type a principal requirement is amechanism cans ing the cutting tool to be rapidly withdrawn as soon as the actual cutting operation is completed, in order to obtain between the single teeth of the cutter grooves as narrow as possible. Assuming a definite pitch, cutter teeth will be obtained with a back face of considerable length, and the cutter itself will be of much greater duration. For rapidlywithdrawing the tool from the revolving piece of work, a cam disc is arranged with its axis parallel to that of the work, a sliding-off cam cooper-i ating with the cam disc. The tool is fixed in a carriage horizontally slidable or in an oscillatable saddle, and every time tooth of the cam disc slides off the oscillating plate, the tool instantaneously jumps back from the work piece, which is revolving ata uniform speed. In the backing-off lathes hitherto known, this speed is in definite proportion to the width of the grooves in the to be backed-01f. Naturally,

higher speeds, for the reason that the tool requires a certain time for movingback from the work piece, the duration ofthe movement corresponding to its length, so that in all cases, where the distance is the same, the time also is the same.) The tool must have returned to its initial position of rest, before it engages the next tooth of the work piece, and under no circumstances should the tool engage to cut the next tooth while the tool is yet vibrating in consequence of its movement, or before it has entirely completed its return movement. the length of a tooth of the work piece to be backed-off to be, for instance, 10 millimeters, the width of the groove 3 mm., and the time required'for cutting the chip of each tooth 1 second, the work piece will turn during this second by one tooth and have invented Assuming Serial N0. 495,614.

one groove and any definite point at its circum 'erence will travel13 mm. .in 1 second. Of thisfpath 3 min, i. e. the width ofthe groove, and oft-he time 3/13 or 023 seconds, are reserved for the return movement of the. tool. If, however, the output of the lathe is to be increased, i. e. if the work piece is to be finished in less time, its revolving speed must. be increased, whereby,

of course, the time for the return movement of the tool is reduced. Thetool would have, no time to return t its initial position andwould cut away the front edge of the subsequent tooth. Theonly possibility of avoiding this drawback would reside in making the grooves of greater width. This would, however, entail a number of other serious drawbacks. The width of every single tooth of the milling cutter would be reduced and, as a consequence, the cutter would becapable of less work. Further, the widths of the grooves would differ from those acceptedas standard widths and, C011. sequently, the cutter would present an unnatural appearance, ,From thisitmust be concluded, that the number ofrevolutions of the work piece to be backed-off is definitely limited in the backing-off lathes hitherto known, and thatthis number cannot be exceeded, unlessthe drawbacks mentionedlare acquiesced in. Therefore, the efliciency ofthe lathe is limited to a definite output. While the adjustment of the pitch according to'different number of teeth has already been possible hitherto with a certain degree of accuracy, either by interchanging copying discs with difierent teeth orby interchanging the wheelsof the change gear, the means'for varying the backing-01f depth of the single teeth have so far not attained to any degree of perfection. This holds good also for such backing-off devices, in which the tool has been fixed into the carriage in reversed order, and in which the work piece spindle is placed outof line with the driving spindle in an oscillating saddle, thelatter being oscillated by means of a cam disc on the driving spindle. In this case, however, the piece of work is not tilted off suddenly. I I

In the ,backing-ofi' lathe embodying the present invention, the work piece spindle is also journalled in an oscillating saddle, its rotary movement, however, is simultaneously transmitted to a cam disc cooperating with an oscillating plate havinga curve portion at its circumference, which plate is adapted to be adjusted and fixed in position. 7

By adjusting this plate, the angle of the 0s cillation of the saddle as well as the backing-ofi depth may be varied. In order to make the number of teeth on the cam disc agree with the number of teeth on the piece of work, suitable gearing is thrown in or effected by placing the oscillatory axis of the oscillating saddle carrying the piece of work outside of the pitch circle of the driving wheel. In this manner a lead is produced during the running with cut, and during thereturn stroke a corresponding lagging results, which latter permits'an increase of the speed of revolution;

In the drawingsattached to this specification and forming part thereof, an embodiment of my invention is illustrated by way of example. 1

In the-drawings I Fig. 1 is a side"elevatiompartly in section and Fig. 2 is a plan View, partly in section while f Fig; 3 discloses t detail, and

Fig. 4: represents the lead and lag dia grammatically. r

'Journalled'in the lathe bed body a is the driving spindle 'b carrying the toothed wheel 0. In addition, an oscillating saddle or frame ddspivoted at the lathe bed in points at c, said points being positioned outside of the pitch-circle of the drivingwheel c. This wheel meshes with a toothed wheel fon a spindle f j ournalled in the oscillating saddle d: The toothed wheel f is driving, by way of the wheel g,-a1gear wheel h, said ear wheel 7L being also positioned in the oscillating-saddle (L on a shaft 2'. To the lat ter the piece of work is fixed, for. instance a milling cutter The gear wheel h actuates, by meansof the gear wheel Z, the shaft 1% journalled in the oscillating saddle.- Shaft m carries a cam disc 91 provided with 12 teeth, as shown in the modification illustrated in thedrawing. This number'of'teeth corresponds to that of the teeth in the milling cutter is to be worked. The cams at of the disc n are in cooperative connection with an oscillating plate 0 adapted to oscillate around the fulcrum pin a, fixed to the lathe bed. The

handle 0' serves to adjust the oscillating plate 0. Ascale arranged at the lathe bed,

but not shown in the drawing, serves for determining the adjustment of plate 0. The

d oscillating plate 0 is provided with a curved section at its circumference,

the curve being preferably the arc of a circle drawn from the center ofthe cam disc n. The oscillating saddled is at rest, if the curve of the oscillating plateis adjusted co-axial with the For the operation of backing-off disc 0 is ad- In this mancam-disc. the piece of work, the curve justed according to the scale. ner the angle of oscillation of the, oscillating saddle and," consequently, the backingoffidepth are pre-determined or adjusted, as the cams a are forcing back the oscillating saddle in accordance with the deflection imparted to them by the curvedisc 0. As soon as the cams n slide off the curve disc 0, the oscillating saddle dwill instantaneously 'urnp back by the same distance and will withdraw the milling cutter is from the tool. The cam disc a may be given any number of teeth. By interchanging the gear wheels h and Z thenumber of teeth in the milling cutter is are made to agree with the number of teeth in the cam disc n.

The leading movement is produced in this manner, that the oscillating saddle d, in its forward oscillation, is describing an arc of a circle around its center of oscillation at c, which is positioned outside of the pitch-circle of the driving Wheel 0, and in in this movement the oscillating saddle advances to meet the tool 9 rigidly clamped to the carriage 9, this advance taking place milling cutter to be 10 teeth" and 'is revolving'once with1n'10 seconds. The cutter will then revolve byone tooth and one groove'within. 1 second. The length of the tooth is 10 mm, the width of'the groove 3 mm.-,'-consequently the distance or pitch of: the teeth is 13 mm. The cutter, therefore, moves by the length of the tooth, i. e. by 10 mm. in 10/ 13:0.7 7 seconds. The remaining time of 0.23 seconds is taken up by the width of the groove and is,;consequ;ently, available for the return movement of the tool. Resulting from the facts, that the fulcrum point e of the oscillating saddle (Z is placed outside of the driving wheel 0, and thatthe wheels sand 7 aremeshing with each other, a lead of .3 mm. is obtained at each stroke, as hasbeen ascertained by ac tual trials. The cutter is moving, within the time of 0.77 seconds, as calculated above, a total distance of 13 mm. The actual cutting work is done only during the distance of 10 mm., and, as a consequenceof the lead, the cutter requires for this" distance of 10 mm., instead of 0.77 seconds, only 2 0 0.59 seconds.

revolution. For the operation of Withdrawing the milling cutter from the tool 21), there remains atotal of 0.23+0.18:O.41 seconds. As, however, only 0.23 seconds are required for this return movement, the time of revolution may be reduced by 0.18 seconds for each groove, in other words, the speed of the revolving piece of ork may be increased by that amount and,therefore, the output of the machine may be increased correspondingly. 1

If the operation of backing-off the millingcutter is 'in circumferential direction is to be combined with a lateral backing-off in an oblique direction, as has been already suggested in the case of backing-off devices with continuous drive, by means of oblique guiding slots, the oscillating movement of the saddle (Z may be made use of in a very simple manner. For this purpose a tongue shaped element 5'', illustrated in Fig. 3, is fixed to the oscillating saddle (Z. This tongue element is adjustable, and formed on it symmetrically are sliding-off edges or faces 8 of any suitable shape. If the saddle (Z is oscillating foward, one of the faces 8 is pressing against a shif-table pin r of the carriage g and thereby produces a lateral displacement of the carriage g simultaneous with the backing-off in the direction of the circumference of the milling cutter it. By throwing the shiftable pin 7' to the right or to the left hand side,.a right-or left hand side backing-off is obtained.

Having thus What I claim as.

described my invention new and desire to secure by Letters Patent of the United States is:

l. A backing-off lathe, comprising, in combination, a driving shaft, a driving Wheel on said driving shaft, a saddle adapted to oscillate in regard to said driving shaft, a shaft journaled in said saddle, said shaft being in geared connection with said driving Wheel a stud on the free end of said shaft, said stud being adapted to receive the cutter blank to be backed off, a tool carria-ge arranged opposite said shaft, a cam disc being in geared connection with said driving wheel, and a curve disc adapted'to coact with said cam disc.

2. A backing-off lathe, comprising, in combination, a driving shaft, a driving Wheel on said driving shaft, a saddle adaptdrivmg Wheel, a studon 3. A backing-off lathe, comprising, in

combination, a driving shaft, a driving wheel on said driving shaft, a saddle adapted to oscillate in regard to said driving shaft, ashaft journaled in said saddle,said shaft being in geared connection With said driving wheel, shaft, said stud being adapted to receive the cutter blank to be backed oil, a tool carriage, arranged opposite said shaft, a cam disc journaled in said saddle and being in geared connection with said driving wheel, a curve disc adapted to coact with said cam disc and stud being adapted to receive the c a stud on the free end of said means for adjusting said curve disc in order 7 to vary the angle of oscillation of the saddle.

4. A backing-off lathe, comprising, in combination, a driving shaft, a driving Wheel on said driving shaft, a saddle adapted to oscillate in regard to said driving shaft,- a shaft journaled in said saddle, said shaft being in geared connection With said driving wheel, a stud on the free end of said shaft, said stud being adapted to receive the cutter blank to be backed off, a tool carriage, arranged opposite said shaft, a cam disc journaled in said saddle and being in geared connection with said driving Wheel, a curve means for adjusting said curve disc in order to vary the angle of oscillation of the said saddle, and a fulcrum pin disposed outside of the pitch-circle of said driving Wheel, said saddle being adapted to oscillate around said pin.

5. A backing-oif lathe, comprising, in combination, a driving shaft, a driving Wheel on said driving shaft, a saddle adapted to oscillate in regard to said drivin shaft, a shaft journaled in said saddle, said shaft being in geared connection with said the free end of said shaft, said stud being adapted to receive the cutter blank to be backed off, a tool carriage, arranged opposite said shaft, a cam disc journaled in said saddle and being in geared connection with said driving Wheel, a curve disc adapted to coact with said cam disc, means for adjusting said curve disc in order to vary the angle of oscillation of said saddle, a fulcrum pin disposed out side of the pitch-circle of said Wheel, said saddle being adapted to oscillate around said pin, and mean for transmitting the rotation of the driving wheel to the shaft journaled in said saddle and to the saidvcam disc 7 in order to produce an additional rotation of said driven shaft and a lead during therunning with cut and a lag duringthe return movement. i y 7 6. A backing-off lathe, comprising, in combination, a shaft, a I tool carriage, an oscillating saddle, and a cam disc adapted to rotate with said shaft, a curve disc, means for adjusting said curve disc, a driving wheel, a driven wheel, a stud on the free end. of said shaft, said stud beingadapted to receive the cutter blank to bebacked off, a fulcrum pin, said saddle adapted to oscillate around said pin, said driving and driven wheels adapted to mesh one with the other and to produce an additional r0- tation of the driven wheel and a. lead during the running with cut and a lag during the return movement, a symmetrically curved element, ashiftable pin adapted to cooperate with said element, said pin fixed adjustably to said tool carriage, saidacooperation. of saidelement and pin adapted toimpart to said tool carriage, by the oscillation of said saddle and the action ofsaidcam disc, a lateral movement for a lateral backing-01f action simultaneous with the oblique movement for a backing-off action in the direction of the circumference.

In testimony whereof I affix my signature in presence of two Witnesses.

J'OSEF DICKESCHEID.-

Witnessesz' ROBERT SCI-IAEFFER,

JACOB SGHNAPS. 

